Bug#1143738: baobab: “/” totals inflated/misattributed by separate LUKS/dm-crypt ext4 mounts under /mnt

[harold]

Package: baobab
Version: 48.0-2+b1
Severity: normal
X-Debbugs-Cc: harold88832 at outlook.com

Dear Maintainer,

baobab (“GNOME Disk Usage Analyzer”) appears to misattribute usage from additional LUKS/dm-crypt-backed ext4 mounts under `/mnt` to `/` totals shown in the Devices & Locations view. This does not match authoritative filesystem usage reported by `df`. 

Environment:
- OS: Debian 13 (amd64), GNOME desktop
- Kernel: 6.12.96+deb13-amd64
- baobab: 48.0-2+b1

Storage layout (relevant):
- `/` is ext4 on `/dev/mapper/debian--13--vg-root`
- `/mnt/data1` and `/mnt/data2` are separate ext4 mounts backed by distinct `/dev/mapper/luks-*` device-mapper targets

Steps to reproduce:
1. Ensure `/` is mounted on LUKS+LVM ext4.
2. Ensure `/mnt/data1` and `/mnt/data2` are separate LUKS-backed ext4 mounts.
3. Open baobab and observe “/”.
4. Add data to `/mnt/data1` and/or `/mnt/data2`.
5. Observe that the “/” totals increase as if including those mounts.

Expected:
- “/” totals should reflect only the ext4 filesystem mounted at `/`.

Actual:
- “/” totals increase in lockstep with usage changes on `/mnt/data1` and `/mnt/data2`.

Evidence (authoritative usage vs GUI):
- `df -h /`:
  /dev/mapper/debian--13--vg-root  448G  213G  213G  50% /
- `df -h /mnt/data1/`:
  /dev/mapper/luks-*  458G   47G  388G  11% /mnt/data1
- `df -h /mnt/data2/`:
  /dev/mapper/luks-*  458G  110G  325G  26% /mnt/data2

Mount-to-device mapping evidence:
- `findmnt -R / -o TARGET,SOURCE,FSTYPE | grep '^├─/mnt'` shows `/mnt/data1` and `/mnt/data2` are separate ext4 mounts sourced from `/dev/mapper/luks-*`.

Comparison:
- In a Debian 13 GNOME VM with a plain additional disk mounted at `/mnt/data` (no LUKS/dm-crypt/LVM), baobab separates root and `/mnt/data` correctly.

Please let me know if you need additional logs/screenshots.

Thanks,
harold


-- System Information:
Debian Release: 13.6
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'stable-security'), (500, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 6.12.96+deb13-amd64 (SMP w/8 CPU threads; PREEMPT)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE not set
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages baobab depends on:
ii  dconf-gsettings-backend [gsettings-backend]  0.40.0-5
ii  libadwaita-1-0                               1.7.6-1~deb13u1
ii  libc6                                        2.41-12+deb13u3
ii  libcairo2                                    1.18.4-1+b1
ii  libglib2.0-0t64                              2.84.4-3~deb13u3
ii  libgraphene-1.0-0                            1.10.8-5
ii  libgtk-4-1                                   4.18.6+ds-2
ii  libpango-1.0-0                               1.56.3-1

Versions of packages baobab recommends:
ii  yelp  42.2-4+deb13u1

baobab suggests no packages.

-- no debconf information